http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Mechanism-based Strain Gradient Plasticity 를 이용한 나노 인덴테이션의 해석
이헌기(H. K. Lee),고성현(S. H. Ko),한준수(J. S. Han),박현철(H. C. Park) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
Recent experiments have shown the "size effects" in micro/nano scale. But the classical plasticity theories can not predict these size dependent deformation behaviors because their constitutive models have no characteristic material length scale. The Mechanism - based Strain Gradient(MSG) plasticity is proposed to analyze the non-uniform deformation behavior in micro/nano scale. The MSG plasticity is a multi-scale analysis connecting macro-scale deformation of the Statistically Stored Dislocation(SSD) and Geometrically Necessary Dislocation(GND) to the meso-scale deformation using the strain gradient. In this research we present a study of nano-indentation by the MSG plasticity. Using W. D. Nix and H. Gao’s model, the analytic solution(including depth dependence of hardness) is obtained for the nano indentation , and furthermore it validated by the experiments.
고성현(S. H. Ko),서재형(J. H. Seo),이필종(P. J. Lee),천명식(M. S. Chun) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.5
In order to remove the shape defect of plate, the levelling process is import in the online plate rolling process. In the levelling process, the process condition is related with the performance of leveller to improve the flatness of plate. In this paper, we carried out the simulation the levelling process with various roll gap to fine out the best condition. However, there is the limitation of levelling process to remove the shape imperfections of plate. Due to the arrangement of work roll of leveller, the plastic deformation cannot be occurred from the end of plate to the distance with the half length of work roll pitch. In the FEM analysis, It is to almost impossible to describe the initial condition of plate before levelling. So, the accuracy of the FEM analysis for the levelling could be poor.
3D-FEM 을 이용한 후판하우징의 피로안정성에 대한 연구
문창호(C. H. Moon),서재형(J. H. Seo),고성현(S. H. Ko),천명식(M.S.Chun),박해두(H. D. Park) 한국소성가공학회 2009 압연 심포지엄 Vol.2009 No.4
The purpose o f this study is to investigate the fatigue safety and deformation of housing in plate rolling process. For this, we carried out 3-dimensional FEM analysis for housing considering design variations of housing structure. It showed that the housing with rounds under a column is benefits to control thickness accuracy of rolled material, due to smaller elastic deformation and maximum effective stress. Also, we calculated the fatigue safety factors, the ratios of the pulsating equivalent fatigue limit to the maximum tensile stresses analyzed using the equipment force and normal rolling force.